The present invention is directed to a device for longitudinally guiding an endless web or belt.
The use of an endless web, for instance, as an endless bolt conveyor, is well known. The cardboard industry, particularly the machines for processing folded boxes, use such belt conveyors for transporting and pressing the flow of boxes in a delivery station which boxes have been previously folded and glued. Usually a delivery station of a folder-gluer is made of a lower endless belt conveyor and an upper endless belt conveyor. The flow of boxes is transferred and pressed therebetween and the pressing, which occurs between the belts, may cause a lateral movement of the upper or lower belt conveyor until they touch the left or right side frame of the delivery station.
Several solutions have already been proposed to obtain a more or less satisfactory guiding of the endless belt conveyors. One of these solutions envisions the channelization of the edge of a belt conveyor using disk which have groooves. These disks with the grooves lie in a horizontal plane of the path of the return run of the conveyor belt and rotate on vertical axes. They are arranged in facing pairs in this plane with one pair at the start of the return path and the other at the end of the return path for the endless belt conveyor.
Another solution uses belt conveyors which are driven by cylinders with a slightly convex roller shape. This shape insures the automatic centering of the endless belt conveyor with great regard to the medium axis or center line of the delivery station.
A further solution proposes a range of rollers acting on the lateral edges of the endless belt conveyor. Unfortunately all of these constructions or solutions soon lead to damage to the conveyor. Since the belts of each of the conveyors is made of a synthetic material, the edges are very often hardened because of the friction with these devices and are often damaged by these guiding elements.